WHO body mass index for age charts overestimate thinness and overweight compared to international and US charts applied to indigenous and non-indigenous mexican children.

Assessments of whether children are thin (low body mass index for age) or overweight are based on body mass index (BMI for age and sex) charts published by the World Health Organization (WHO), the International Obesity Task Force (IOTF), and the US Centers for Disease Control and Prevention (CDC). We aimed to determine whether these charts indicated different prevalence of thinness and overweight (obesity included) in indigenous and nonindigenous school aged children from different regions and ethnic groups in Mexico. A probability proportional to size, cluster sampling method was employed in four regions of the country. We recruited 1,731 children aged 7.0-9.9 (507 indigenous from six ethnic groups and 1,224 non-indigenous). BMI was calculated according to age, and thinness and overweight classifications were compared according to cutoff values in the WHO, IOTF, and CDC references. The WHO reference generated the highest rates for thinness (12.5%) and overweight (30%) in children across regions and ethnic groups. The CDC reference estimated the lowest rates of thinness in children (5.5%), and the IOTF reference estimated the lowest rates of overweight (24.7%). Estimates of both thinness (8.3%) and overweight (13.4%) rates were lower in indigenous than non-indigenous groups (14.3% and 37.5%, respectively). The WHO BMI for age chart estimated higher rates of thinness and overweight in children compared to the CDC and IOTF charts. Because thinness as indicator of undernutrition status is relatively new, differences in body composition among indigenous and non-indigenous children May justify the need for more appropriate screening criteria to compare the growth status.